Dota Planet, Branch of the Iron Tree

Toss accounts have a medal (cf 'Medals' tab of 'Quests' link) that is conferred once the player gets 'Branch of the Iron tree' by performing an expedition to the 'Dota Planet'. Until one gets 'Branch of the Iron tree', one cannot build one's own Investigator ships (and hence must buy them from the Bestiary).

I've never heard of the 'Dota Planet' before playing as a Toss, and I can find no mention of it in the (english) forums. Even my knowledgeable mentor is unsure about this tidbit. Players that I've messages are also in the dark.

Can anyone fill me in? Maybe even point me to in-game info or a forum posting that I may have somehow missed?